This invention relates to optical image sensing devices and is specifically directed to a new and improved heterodyne imaging sensor utilizing a frequency coding technique.
The use of heterodyne techniques in optical information reading is old in the art as shown by way of example in the U.S. Pat. No. 3,868,658 to Kiemle which utilized an optical memory information bearing light beam and a frequency shifted light beam merged together to scan a detector column by column and row by row.
In another U.S. Pat. No. Re. 30,166 to Lee, a heterodyne technique was utilized to increase the signal-to-noise ratio during the read-out stage which utilized an array of detectors to receive superimposed beams at the reconstructed image plane.
Both the above patented systems are of the scanning type utilizing arrays of detectors and mechanical scanning devices.
This invention is a heterodyne imaging sensor without an array of detectors and without mechanical scanning which utilizes a frequency coding technique.